Microstructural characteristics of sandwiched T-shaped metamaterials for three-port splitting

Abstract

This paper presents a polarization-insensitive sandwiched three-port beam splitting grating at normal incidence. The grating adopts a sandwiched structure. Based on the rigorous coupled-wave analysis (RCWA) and the simulated annealing algorithm, the grating parameters are optimized to obtain the diffraction efficiencies of 32.83% at 0th order and 32.87% at ±1st orders for transverse electric polarization, and 32.63% at 0th order and 32.39% at ±1st orders for transverse magnetic polarization. Meanwhile, the calculation results of the finite element method are in general agreement with those of RCWA. In addition, the analysis results of grating period, duty cycle, and wavelength bandwidth further demonstrate the good wavelength bandwidth of the grating and its feasibility for practical production. Therefore, the grating can be widely used in actual production.